Antenna structures have been developed to provide light-weight antenna arrays including “active” or “phased” array antennas. However in many cases the lightweight materials and carefully calibrated electrical elements produce a delicate antenna structure. At the same time, these lightweight antenna structures may be deployed on platforms that are exposed to various thermal and structural loads and possibly harsh environmental conditions.
For example, one application for lightweight antenna structures is high-altitude surveillance, such as high-altitude balloons. During the balloon's flight, temperature conditions through the atmosphere may change considerably, causing the balloon material to expand or contract. The material of the balloon itself differs from the antenna structure and may have a different coefficient of thermal expansion. Due to the mismatch in thermal expansion between the balloon platform and its antenna payload, the balloon may expand more or less than the antenna structure, thereby stressing the joint or bond between the balloon and the antenna. These “thermal” stresses due to differential thermal expansion can cause failure of the joint or the antenna structure itself, or cause other problems such as warping or mis-alignment of the antenna structure. Prior attachment mechanisms include direct adhesive bonding, mechanical joints, and lanyards. Adhesively bonding the panel directly to the balloon material does not account for the thermal mismatch between the materials, or variations in the two surfaces (such as surface features on the panel, or curvature of the balloon). Rigid mechanical joints at the corners of the panels can lead to structural failure at the corners. Lanyards, loops, and other similar attachments may not be precise enough for alignment of the antenna array, and the antenna panels may bend, swing, or move out of place. These attachment structures can also add significant weight to the system.
Accordingly there is still a need for an attachment mechanism for attaching lightweight antenna structures to a platform exposed to various thermal and/or other stresses.